16. Influence of soil fertility on kernel-row number. Some years ago two 12-row inbred lines and the F1 cross were grown on sand of extremely poor fertility and on very rich soil. The test was carried on during two seasons and the number of plants involved were 281 on rich soil and 287 on poor. The row-number means are compared in the following table:
| Rich soil | Poor soil | Difference | |
| Inbred A | 12.6 | 11.1 | 1.5 |
| Inbred B | 12.3 | 10.6 | 1.7 |
| F1 A-B | 12.4 | 11.5 | 9.3 |
| All | 12.4 | 11.1 | 1.3 |
The effect of extreme differences in soil fertility on number of kernel rows is obviously greater than that shown as heterosis. Neither effect is sufficient seriously to mask genetic differences in studies of kernel-row numbers.
R. A. Emerson